JP7202019B2 - Method for manufacturing cardboard adhesive - Google Patents

Description

The present invention relates to a method for producing an adhesive for corrugated board.

In general, corrugated board is manufactured by sandwiching corrugating corrugating paper between liner papers and adhering them together. Various adhesives (binders) are used to bond the corrugating medium and the liner paper together.

When making corrugated cardboard sheets, the glue that is used for the single layer, which is the back side of the cardboard box, is called single glue. Also, the glue used on the front side of the cardboard box is called double glue.

A machine called a corrugator is used to join the cardboards together. The three corrugated baseboards are a front liner, a corrugating medium and a back liner. At the single facer, the corrugated core is formed into a corrugated shape, glued, and attached to the back liner to make a single-faced corrugated cardboard. At the double facer, apply glue to the other side of the single-faced cardboard and attach it to the front liner. This produces a long cardboard sheet.

Adhesion is performed in the order of permeation adhesion, interfacial adhesion, and cohesion adhesion. In the permeation adhesion, the size liquid penetrates into the paper layer from the surface of the liner and the corrugating medium, filling the gaps between the intertwined fibers and strongly bonding them together. Interfacial adhesion is adhesion due to intermolecular attractive forces at the interface between the surface of the liner and core and the adhesive. In the cohesive adhesion, the adhesive permeated into the base paper and the Jorda bond component of the interfacial adhesion form a group, and the intermolecular bonds of the starch itself are also added to adhere to it.
A balance between permeation adhesion and interfacial adhesion is important.
On the single facer side, interfacial adhesion is achieved by pressurization, and on the double facer side, penetration adhesion is achieved by close contact.

For a long time, cornstarch, which is relatively inexpensive and stable in terms of quality and supply, has been widely used as a paste for cardboard.

Mixing water, starch, caustic soda, and borax to make paste for cardboard is called gluing.
When blending, the blending ratio, blending timing, temperature during blending, and the quality of the starch used determine the quality of the resulting paste, and the productivity of corrugated board production varies.

As for the amount of caustic soda used, even a change in the addition rate of about 0.01% by mass has a large effect on the performance of the paste, so the adjustment of the addition rate must be done carefully.
Caustic soda lowers the gelatinization starting temperature of starch and increases the viscosity at the time of gelatinization.
Caustic soda facilitates the transfer of glue to the flute tops. In addition, caustic soda gelatinizes the carrier starch in a short time during carrier formation. Caustic soda is designated as a non-medicinal and deleterious substance, and safety must be considered first when handling it.

In the presence of caustic soda, borax undergoes a pseudo-crosslinking reaction with starch to increase its apparent molecular weight, increase adhesive strength, and improve initial adhesion. Also, borax increases the water retentivity of the paste and strengthens the gel strength.
On the other hand, if an excessive amount of borax is added, the fluidity of the paste becomes poor and the paste becomes hard and brittle when dried and adhered. becomes.

Cornstarch is characterized by its extremely high purity and uniformity in quality, and is used as a paste for cardboard. The quality of cornstarch for use as a paste for corrugated board is determined by the moisture content, the starting temperature of alkali gelatinization, the quality of the raw material corn, and the production conditions such as the soaking process.

Brabender stirs a sample in which starch is dispersed in an aqueous solution while increasing the temperature by 1.5°C per minute. It is an analytical instrument that can graph the situation.

Conventionally, paste-making methods for corrugated board mainly include the stain hole method and the no-carrier method.

In the Stein-Hall method, carrier starch is dispersed in water and caustic soda is added in the carrier part, and main water is added in the main part, and after the main starch is added, borax is added.
The paste obtained by the Stein-Hall method has low water retention and low B-type viscosity.

In the carrier-free method, there is no carrier part, and after adding starch to water, caustic soda is added and boric acid is added.
The paste obtained by the carrier-free method is semi-swollen, has starch granules remaining, is in a mixed state of various sizes, and gelatinizes quickly. In addition, the sizing agent obtained by the carrier-free method has low shear resistance, and because each starch particle retains a lot of water, it hardly penetrates into the paper. The reaction time fluctuates depending on the temperature, and as a result, the finished viscosity tends to fluctuate.

When corrugated cardboard sheets are manufactured, deformation called warpage occurs, and countermeasures against it have become an issue. When passing through the hot plate, the corrugated paper and liner paper also receive heat from the hot plate, and the moisture contained in the corrugated paper and liner paper evaporates rapidly, causing the paper fibers to expand and contract, causing the corrugated board to become flat. There is warpage that disappears.

As adhesives for cardboard, for example, those described in Patent Literature 1 and Patent Literature 2 are known.
Patent document 1 and patent document 2 below are given as publication examples.

JP 2017-95674 A JP 2019-163392 A

In the method for producing the cardboard adhesive according to Patent Documents 1 and 2, the carrier portion is selected from the group consisting of trimetaphosphate, adipic anhydride, phosphoric anhydride, phosphorus oxychloride, acrolein, epichlorohydrin, glyoxal, and melanin. One or more cross-linking agents and starch are used.

The corrugated cardboard adhesive according to Patent Document 2 uses the stain hole method, but the corrugated cardboard adhesive according to the manufacturing method of the present invention does not use the stain hole method.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object thereof is to provide a method for producing an adhesive for corrugated board that has high adhesive strength and is less susceptible to the type of water and starch.

The method for producing an adhesive for corrugated board according to the present invention is a method for producing an adhesive for corrugated board for adhering corrugating medium and liner paper. a second step of adding main water; a third step of adding main starch; a fourth step of adding secondary caustic soda; and a fifth step of adding boric acid . The carrier borax ratio indicating the mass of borax with respect to the total mass of the carrier part produced in the process is 0.01 to 0.10% by mass, and in the first step and the third step, the amount of starch in the carrier part and the amount of starch in the main part A secondary caustic soda concentration in the range of 5.0 to 30.0% by mass in the fourth step, including a carrier ratio indicating the weight ratio of starch in the carrier part to the total starch amount of 3.0 to 20.0% by mass. of secondary caustic soda .

The method for producing the adhesive for cardboard according to the present invention comprises adding not only carrier starch but also borax to water in the carrier portion of the paste making method. Further, after the carrier portion is produced, caustic soda is added in multiple portions in the main portion.

In the raw material to be used, thickening of the carrier part is suppressed by using borax in the carrier part. By setting the secondary caustic concentration low, the main starch can be uniformly swollen. Since waste water can be used, environmentally friendly production is possible, and an adhesive that contributes to environmental conservation can be provided. By limiting the composition ratios used in the carrier part and the main part, a sizing agent of stable quality can be obtained.

By using the method for producing an adhesive for cardboard according to the present invention, a paste having excellent adhesive properties can be obtained regardless of the type and quality of raw materials used, mainly cornstarch starch. This has the effect of improving productivity and reducing costs.

By using the method for producing an adhesive for cardboard according to the present invention, a paste having excellent initial adhesiveness can be obtained. This has the effect of improving productivity.

By using the method for producing an adhesive for corrugated board of the present invention, it is possible to produce a high-quality corrugated board sheet with excellent adhesive strength. This has the effect of improving quality.

In the method for producing an adhesive for corrugated cardboard according to the present invention, a paste having excellent adhesiveness and having a stable viscosity can be obtained even when waste water is used for making paste. As a result, the wastewater can be used, which has the effect of environmental measures and productivity improvement.

In the method of manufacturing the adhesive for cardboard according to the present invention, the viscosity of the paste used can be freely set. This has the effect of stably producing glue.

The schematic diagram of the manufacturing method of this invention. 4 is a graph showing Brabender viscosity and reaction temperature according to Example 1 of the present invention and Comparative Example 1 of the Stein-Hall method.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

(first embodiment)
FIG. 1 shows the process of one embodiment of the method for producing the adhesive for cardboard according to the present invention. In the carrier part of the present invention, not only carrier cornstarch starch but also borax are added to and dispersed in water. Further, caustic soda is added to the carrier portion. In the main section, main water is added, main cornstarch starch is added, and then secondary caustic soda is added stepwise. Furthermore, boric acid is added to the main portion.
In this embodiment, the step of adding and dispersing not only starch but also borax to water and further adding caustic soda is called the carrier part.

Hereinafter, the present invention will be described in more detail with reference to specific Example 1 and Experiments 1 to 4 of the present invention, but the scope of the present invention is limited to Example 1 and Experiments 1 to 4 below. not a thing

<Example 1>
The glue was prepared as shown in Table 1 according to the new method of manufacturing the corrugating adhesive of the present invention. The obtained paste was measured for paste viscosity and paste adhesive strength as described below.

Table 1 shows experimental data of Example 1 of the method for producing an adhesive for cardboard according to the present invention.

(Preparation of paste liquid)
In Example 1, in the carrier part, not only 100 g of carrier starch but also 0.6 g of borax were added and dispersed in 1250 g of water at 40°C. Furthermore, 70 g of caustic soda is added to the carrier part. In the main portion, 1680 g of main water is added, 900 g of main starch is added, and then 30 g of secondary caustic soda is added step by step for the first main portion, 5 g for the first addition, and 5 g for the second addition. Furthermore, 12 g of boric acid is added to the main part.

(Measurement of paste liquid viscosity after paste making)
Ford cup viscosity (seconds) and B-type viscosity (mPa·s) of the sizing solution were measured. The B/F index was calculated from Ford cup viscosity and B-type viscosity.

(Measurement of glue adhesive strength after making glue)
Adhesion strength (N) of the sizing solution was measured at pressure bonding times of 1, 2, 3, 4, 5, 10, 13, 15 and 18 seconds. Crimping times of 1 second, 2 seconds and 3 seconds are high speed conditions, crimping times of 4 seconds, 5 seconds and 10 seconds are medium speed conditions, and crimping times of 13 seconds, 15 seconds and 18 seconds are low speed conditions.

In Example 1 of the present invention, the Ford cup viscosity was 30 seconds, the B-type viscosity was 400 mPa s, and the B/F index was 13.3. was taken.

Next, Experiment 1 is an experiment conducted in Example 1 of the present invention under the condition that the carrier portion has a borax rate of 0% by mass to 0.13% by mass.

Experiment 2 is an experiment conducted in Example 1 of the present invention under the condition that the concentration of secondary caustic soda in the main portion is 5% by mass to 50% by mass.

Experiment 3 is an experiment conducted in Example 1 of the present invention under the condition that the overall carrier ratio is 3% by mass to 33% by mass.

<Experiment 1: Carrier borax rate>
The paste was prepared as shown in Table 2 according to the new method of manufacturing the corrugating adhesive of the present invention. The obtained paste was measured for paste viscosity and paste adhesive strength as described below.
Experiment 1 is an experiment conducted in Example 1 under the condition that the carrier portion has a borax rate of 0% by mass to 0.13% by mass.

Table 2 shows experimental data of Experiment 1 of the method for producing the adhesive for cardboard according to the present invention.

(Preparation of paste liquid)
In Experiment 1, in the carrier part, not only 100 g of carrier starch was added to 1250 g of water at 40 ° C., but also 0.2 g of borax in Experiments 1-1, 1-2, 1-3, 1-4, and 1-5. , 1.3 g, 0.0 g, 0.07 g, and 1.8 g are added and dispersed, and the carrier borax rate is 0.01% by mass, 0.09% by mass, 0% by mass, 0.005% by mass, and , 0.13 mass %. Furthermore, 70 g of caustic soda is added to the carrier part. In the main portion, 1680 g of main water is added, 900 g of main starch is added, and then 30 g of secondary caustic soda is added step by step for the first main portion, 5 g for the first addition, and 5 g for the second addition. Furthermore, 12 g of boric acid is added to the main portion.

(Measurement of paste liquid viscosity after paste making)
Ford cup viscosity (seconds) and B-type viscosity (mPa·s) of the sizing solution were measured. The B/F index was calculated from Ford cup viscosity and B-type viscosity.

(Measurement of glue adhesive strength after making glue)
Adhesion strength (N) of the sizing solution was measured at pressure bonding times of 1, 2, 3, 4, 5, 10, 13, 15 and 18 seconds. Crimping times of 1 second, 2 seconds and 3 seconds are high speed conditions, crimping times of 4 seconds, 5 seconds and 10 seconds are medium speed conditions, and crimping times of 13 seconds, 15 seconds and 18 seconds are low speed conditions.

The viscosity change over time of the prepared paste liquid is examined with respect to the carrier borax concentration, which is the experimental result of Experiment 1.

As the concentration of carrier borax increased and the amount of borax added to the carrier part increased, the viscosity of the prepared paste increased. The B/F index was less than 10 when the carrier borax concentration was 0.005% by mass or less, and the B/F index was 20 or more when the carrier borax concentration was 0.09% by mass or more.
When the carrier borax concentration was 0.01% by mass or more and 0.09% by mass or less, the B/F index was 10 or more and 20 or less.

In Experiment 1, it was found to be appropriate when the carrier borax rate was 0.01% by mass to 0.10% by mass.

<Experiment 2: Secondary caustic soda concentration>
The paste was prepared as shown in Table 3 by the new method of making the corrugating adhesive of the present invention. The obtained paste was measured for paste viscosity and paste adhesive strength as described below.
Experiment 2 is an experiment conducted in Example 1 under the condition that the concentration of secondary caustic soda in the main portion is 5% by mass to 50% by mass.

Table 3 shows experimental data of Experiment 2 of the method for producing the adhesive for cardboard according to the present invention.

(Preparation of paste liquid)
In Experiment 2, not only 100 g of carrier starch but also 0.6 g of borax were added and dispersed in 1250 g of water at 40° C. in the carrier part. Furthermore, 70 g of caustic soda is added to the carrier part. In the main part, in Experiments 2-1, 2-2, 2-3, 2-4, and 2-5, 1480 g, 1610 g, 1680 g, 1680 g, and 1690 g of main water were added, and 900 g of main starch was added. After that, secondary caustic soda with a secondary caustic soda concentration of 5% by mass, 10% by mass, 30% by mass, 35% by mass, and 50% by mass is gradually added to the main initial 150 g, the first additional 25 g, the second additional 25 g, Add 25g for the third addition, 75g for the first addition, 13g for the first addition, 13g for the second addition, 25g for the initial main, 4g for the first addition, 22g for the first main, 4g for the first addition, and 15g for the first main and 3g for the first addition. . Furthermore, 12 g of boric acid is added to the main portion.

(Measurement of paste liquid viscosity after paste making)
Ford cup viscosity (seconds) and B-type viscosity (mPa·s) of the sizing solution were measured. The B/F index was calculated from Ford cup viscosity and B-type viscosity.

(Measurement of glue adhesive strength after making glue)
Adhesion strength (N) of the sizing solution was measured at pressure bonding times of 1, 2, 3, 4, 5, 10, 13, 15 and 18 seconds. Crimping times of 1 second, 2 seconds and 3 seconds are high speed conditions, crimping times of 4 seconds, 5 seconds and 10 seconds are medium speed conditions, and crimping times of 13 seconds, 15 seconds and 18 seconds are low speed conditions.

The change in viscosity over time of the prepared paste liquid is investigated with respect to the secondary caustic soda concentration, which is the experimental result of Experiment 2.

The B/F index was less than 10 when the secondary caustic soda concentration was 35 mass % or more. When the secondary caustic soda concentration was 5 mass % or more and 30 mass % or less, the B/F index was 10 or more and 20 or less.
As the secondary caustic soda concentration decreased, the viscosity of the prepared paste increased as the amount and frequency of addition of secondary caustic soda in the main part increased.

In Experiment 2, it was found to be appropriate when the secondary caustic soda concentration was 5.0% by mass to 30.0% by mass.

<Experiment 3: Carrier rate>
Pastes were prepared as shown in Table 4 according to the new method of making the cardboard adhesive of the present invention. The obtained paste was measured for paste viscosity and paste adhesive strength as described below.
Experiment 3 is an experiment conducted in Example 1 under the condition that the overall carrier ratio is 3% by mass to 33% by mass.

Table 4 shows experimental data of Experiment 3 of the method for producing the adhesive for cardboard according to the present invention.

(Preparation of paste liquid)
In Experiment 3, in the carrier part, 1250 g of water at 40 ° C. was added to 30 g, 50 g, 200 g, 300 g, and Add 0.6 g of borax as well as 330 g and disperse. Furthermore, 70 g of caustic soda is added to the carrier part. In the main portion, 1680 g of main water was added, and in Experiments 3-1, 3-2, 3-3, 3-4, and 3-5, 970 g, 950 g, 800 g, 700 g, and 670 g of main starch were added. After that, add secondary caustic soda in stages: 30 g for the first main, 5 g for the first addition, 5 g for the second addition, 5 g for the third addition, 30 g for the first main, 5 g for the first addition, 5 g for the second addition, 30 g for the first main, and 5 g for the first addition. , 5g second addition, 30g main first, 5g first addition, and 30g main first, 5g first addition. Further, 12 g of boric acid is added to the main portion. In Experiments 3-1, 3-2, 3-3, 3-4, and 3-5, the carrier rate was 3% by mass, 5% by mass, 20% by mass, 30% by mass, and 33% by mass. Become.

(Measurement of paste liquid viscosity after paste making)
Ford cup viscosity (seconds) and B-type viscosity (mPa·s) of the sizing solution were measured. The B/F index was calculated from Ford cup viscosity and B-type viscosity.

(Measurement of adhesive strength of paste liquid after making paste)
Adhesion strength (N) of the sizing solution was measured at pressure bonding times of 1, 2, 3, 4, 5, 10, 13, 15 and 18 seconds. Crimping times of 1 second, 2 seconds and 3 seconds are high speed conditions, crimping times of 4 seconds, 5 seconds and 10 seconds are medium speed conditions, and crimping times of 13 seconds, 15 seconds and 18 seconds are low speed conditions.

The viscosity change over time of the prepared paste liquid is investigated with respect to the carrier rate, which is the experimental result of Experiment 1.

The B/F index was less than 10 when the carrier ratio was 30% by mass or more. When the carrier ratio was 3% by mass or more and 20% by mass or less, the B/F index was 10 or more and 20 or less.
As the carrier ratio decreased, the viscosity of the prepared paste increased as the amount of starch added in the main portion was larger than that in the carrier portion.

In Experiment 3, it was found to be appropriate when the carrier rate was 3.0% by mass to 20.0% by mass.

<Experiment 4: Stein Hall Method and No Carrier Method>
It is not the system of the present invention. Pastes were prepared as shown in Table 5 by the Stein Hall method and the no carrier method. The obtained paste was measured for paste viscosity and paste adhesive strength as described below.

Table 5 shows experimental data for the Stein Hall method and the no-carrier method.

Comparative Example 1 is the Stein Hall method.
In Comparative Example 1, 120 g of carrier cornstarch was dispersed in 1250 g of water at 40° C. and 80 g of caustic soda was added to the carrier portion, and 1680 g of main water was added to the main portion. .

Comparative Example 2 is a no-carrier system.
In Comparative Example 2, no carrier portion was used, and after adding 1000 g of main cornstarch to 2850 g of water, 190 g of caustic soda and 12 g of boric acid were added.

In the Stein Hall method, the B-type viscosity/cup viscosity is 8.9 or less, but the B-type viscosity/cup viscosity of the new method of manufacturing the adhesive for cardboard according to the present invention was 9.0 or more. .

In the no-carrier method, the B-type viscosity/cup viscosity is 21 or more, but the B-type viscosity/cup viscosity of the new method of manufacturing the adhesive for cardboard according to the present invention is 20.0 or less.

Next, FIG. 2 shows a comparison of Brabender viscosity and reaction temperature between Example 1 of the present invention and Comparative Example 1 of the Stein-Hall method.

(Measurement of Brabender viscosity after paste making)
Using a Brabender, the Brabender viscosity (unit: BU) of the sample of Example 1 of the present invention and the sample of Comparative Example 1 of the Stein Hall method was measured.

The system of Example 1 of the present invention had a higher Brabender viscosity than the conventional Stein-Hall system of Comparative Example 1. Further, in the method of Example 1 of the present invention, swelling, decrease, and viscosity increase were observed in the same manner as in the Stein Hall method.

Next, the distribution of experimental results of adhesive strength against B-type viscosity under high-speed conditions according to the manufacturing method of the present invention is examined.
Investigate the distribution of experimental results of adhesive strength versus B-type viscosity at low speed conditions according to the manufacturing method of the present invention.

Table 6 shows experimental data of Example 1 and Experiments 1 to 3 of the manufacturing method of the adhesive for cardboard according to the present invention.

Table 7 shows experimental data of changes in adhesive strength over time in Experiments 1 to 3, the Stein Hall method, and the no-carrier method of the manufacturing method of the adhesive for cardboard according to the present invention.

Example 1 of the manufacturing method of the invention has a B/F index of 13.3 and an adhesion strength of 83 N under high speed conditions. Under these conditions, the bond strength was 37N.
The manufacturing method of the adhesive for cardboard according to the present invention had a higher B/F index and a higher adhesive strength under high speed conditions than the Stein Hall method.

Example 1 of the manufacturing method of the invention has a B/F index of 13.3 and an adhesion strength of 83 N under high speed conditions. The adhesive strength was 20N under these conditions.
The manufacturing method of the adhesive for cardboard according to the present invention has a lower B/F index than the no-carrier method, but the bonding strength is very high under high-speed conditions.

Example 1 of the manufacturing method of the invention has a B/F index of 13.3 and an adhesion strength of 330 N under low speed conditions. Under these conditions, the bond strength was 230N.
The manufacturing method of the corrugated cardboard adhesive of the present invention had a higher B/F index than the Stein Hall method, and the adhesive strength was also very high under low speed conditions.

Example 1 of the manufacturing method of the invention has a B/F index of 13.3 and an adhesion strength of 330 N under low speed conditions. Under these conditions, the bond strength was 283N.
The method for manufacturing the corrugated cardboard adhesive of the present invention had a lower B/F index than the no-carrier method, and the adhesive strength was high at low speed conditions, but when the carrier borax rate was low and the secondary caustic soda concentration was high. Adhesion strength was low.

In the experimental examples of the manufacturing method of the present invention, the adhesive strength increased over time from the high speed condition to the medium speed condition from the crimping time. No change or a little smaller.

In the comparative example of the experiment by the production method of the present invention, the adhesive strength increased over time from the high speed condition to the medium speed condition from the crimping time, and then the adhesive strength under the medium speed condition peaked, and from the medium speed condition to the low speed condition. became a little smaller.

(Second embodiment)
Wastewater can be used in the method for producing the corrugated board adhesive of the present invention. Water used as carrier water or main water is not particularly limited, and waste water can be used. Other basic configurations of the other embodiments are the same as those of the first embodiment.

(Other examples)
Various starches can be used in the main portion of the method for producing the corrugated cardboard adhesive of the present invention. The starch used for the main portion is not particularly limited, and starch derived from various raw materials can be used. For example, corn starch, high amylose corn starch, tapioca starch, wheat starch, potato starch, sweet potato starch and the like can be used. Other basic configurations of the other embodiments are the same as those of the first embodiment.

As described above, the present invention is by no means limited to the above embodiments, and can be implemented in various embodiments without departing from the scope of the invention.

Claims (3)

A method for producing a corrugated cardboard adhesive for bonding core paper and liner paper, comprising:
a first step of adding carrier starch and borax to carrier water and adding caustic soda;
a second step of adding main water;
a third step of adding main starch;
a fourth step of adding secondary caustic soda;
a fifth step of adding boric acid;
Contains a carrier borax rate of 0.01 to 0.10% by mass, which indicates the mass of borax with respect to the total mass of the carrier portion produced in the first step,
In the first step and the third step, the carrier ratio indicating the weight ratio of the starch in the carrier part to the sum of the starch amount in the carrier part and the starch amount in the main part is 3.0 to 20.0% by mass,
A method for producing an adhesive for corrugated board, wherein in the fourth step, secondary caustic soda having a secondary caustic soda concentration in the range of 5.0 to 30.0% by mass is used. 2. The method of claim 1, wherein in the fourth step, secondary caustic soda is added stepwise, and when the cup viscosity measured each time the addition reaches a predetermined value, the step is stopped, and then in the fifth step, boric acid is added. 3. The method for producing the corrugated cardboard adhesive according to . a step of adjusting an adhesive by using the method for manufacturing an adhesive for corrugated board according to claim 1 or 2; a step of applying the adjusted adhesive to core paper; and a step of applying the adhesive. A method of manufacturing corrugated board, comprising a step of laminating core paper and liner paper.

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